The invention relates to systems and methods for performing spectroscopy.
A number of conventional spectroscopy techniques are used to analyze samples through the study of an interaction between the sample and light. These conventional techniques include direct absorption spectroscopy and cavity ring-down spectroscopy (CRDS). Direct absorption spectroscopy involves directly measuring an intensity transmission through an optical cavity with a sample, and comparing the results to a measured intensity transmission through an empty optical cavity. The absorption of light by the sample changes as a function of frequency, which enables the generation of an absorption spectrum of the sample. Direct absorption spectroscopy is effective when measuring relatively large amount of sample and/or a sample that interacts strongly with light. Direct absorption spectroscopy becomes less effective when analyzing a small amount of sample and/or a sample that interacts weakly with light. For such measurements, CRDS is generally more effective. CRDS measures ringdown times, i.e. amounts of time it takes for light that excites a resonant optical chamber and interacts with a sample to decay to a fraction of its initial intensity, for example 1/e). An absorption spectrum can be generated from measured ring-down times.